Aerial lift device



1963 J. J. SHENNUM 3,100,025

AERIAL LIFT DEVICE Filed Nov. 1, 1961 3 Sheets-Sheet 1 v s k F John L. Shennum L/ INVENTOR.

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1953 J. J. SHENNUM 3,100,025

AERIAL LIFT DEVICE I Filed Nov. 1, 1961 3 Sheets-Sheet 3 l Fig.

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BY M 8% United States Patent 3,100,025 AERIAL LIFT DEVICE John L. Shennum, Box 173, Circle, Mont. Filed Nov. 1, 1961, Ser. No. 149,283 8 Claims. (Cl. 1822) This invention relates to devices for elevating platform structures so as to enable workmen to perform services at elevated positions.

It is therefore a primary object of the present invention to provide an effective, compact and portable lifting device th-at may be mounted on a truck bed and power operated for rapid movement from a folded condition to an upwardly extended position maintaining the platform structure level throughout so as to safely carry a workman thereon.

Portable lift devices for platform structures have heretofore been devised utilizing many different arrangements for achieving the general purposes of this invention. The lift device of the present invention however achieves the purpose in a novel and advantageous manner, avoiding many of the undesirable features of lift devices heretofore used. The lift device of the present invention, therefore, does not involve any parallelogram linkage in order to maintain the platform structure level. The arrangement of the present invention therefore avoids the disadvantages inherent in the use of parallelogram linkages because of the limitation in its range of movement due to linkage interference and also avoids the use of two or more closed linkage assemblies heretofore resorted to in order to overcome the limitation on range of movement. The level position of the platform in the present device is also maintained without reliance on any ratio gearing, complex interrelating motion controlling system or by use of extensible link members. Instead, a positive simple linkage coordinated with limited unfolding movement of articulated boom members is utilized to maintain the platform structure level throughout avoiding the expense and complexity of gearing and servo systems as well as the obvious disadvantage of extensible link members.

A further object of this invention is to provide an aerial lift device capable of achieving the aforementioned objectives in an advantageous manner and further utilizing a plurality of separate power input devices capable of more etliciently transmitting the lifting force to the platform structure and operative to simultaneously produce upward angular movement of the platform carrying boom and elevation of the boom connections to the support.

A still further object of this invention is to provide an aerial lift device having a novel linkage arrangement whereby the lifting assembly may be folded into a more compact arrangement on the supporting base as compared with lifting devices having comparable extended weights.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a top plan view of the aerial lift device of the present invention shown mounted on a truck bed;

FIGURE 2 is a side elevational view of the aerial device illustrated in FIGURE '1, shown in its folded condition;

FIGURE 3 is a partial side elevational view of the aerial device shown in its extended condition;

FIGURE 4 is a hydraulic circuit diagram of a power control system associated with the aerial lifting device;

FIGURE 5 is a sectional view taken from the plane indicated by the section line 55 in FIGURE 2; and

3,100,025 Patented Aug. 6', 1963 Ice FIGURE 6 is a sectional view taken through a plane indicated by the section 6-6 in FIGURE 2.

Referring now to the drawings in detail it will be observed from FIGURES 1 and 2 that the aerial lift device generally referred to by reference numeral 10 is mounted on the bed 12 of a truck generally referred to by reference numeral I14. The aerial device it) may be rotatably mounted on the truck bed 12 by means of a rotor 16 supporting thereabove in any suitable manner the base support member 18 of the aerial device 10.

The base member 18 as more clearly seen in FIGURE 3 pivotally mounts at opposite ends thereof, a lifting assembly generally referred to by reference numeral 20 and a positioning assembly generally referred to by ref erence numeral 22. Operatively connected to the upper end of the assemblies 20 and 22 to form an articulated platform carrying structure, is a platform or basket structure 24 adapted to carry and support workmen. The assemblies 20 and 2 2 are therefore elevated from their folded parallel position as illustrated in FIGURE 2 to an upwardly extended unfolded position as illustrated in FIGURE 3. A power operated system generally referred to by reference numeral 26 as illustrated in FIGURE 4 is therefore utilized in connection with the aerial lift device lil to effect elevation and lowering of the platform structure 24.

The lifting assembly 20* is operative to elevate the platform structure 24 by upward displacement thereof. The assembly 20, therefore, includes a lever or crank member 28 one end of which is pivotally connected to the base 18 by means of the upwardly projecting portion 30 thereof. The opposite end of the lever member 28 has a projecting pivot portion 32 by means of which it is pivotally connected to a column or boom supporting member 34. "llhe column member 34 is a rigid member which includes a section 36 that may be made of suitable plastic material for electrically insulating the platform from grounding or from some other non-conductive material for achieving the same purpose such as a section made of laminated wood. The column member 34 is otherwise constructed of any suitable material capable of sustaining the load stresses applied thereto such as box steel. A connecting member 38 is rigidly connected to the upper end of the column member 34' by means of which the column member 34 is pivotally connected at pivot 40 to the platform structure 24 and by means of pivot 42 to the upper end of the positioning assembly 22.

The positioning assembly also includes an elongated rigid boom member 44 similar in construction to the column member 34 but longer than the column member 34. The boom member 44 therefore also includes a section 46 made of non-conductive material as more clearly seen in FIGURE 5 similar to that described with respect to the section 36 of the column member 34. The other portions of the boom member 44 are constructed in a manner similar to that described with respect to the column member 34 and .as more clearly seen in FIGURE 6. The upper end of the boom member 44 is therefore pivotally connected by the pivot 42 to the connecting member 38 while the other end of the boom member is pivotally connected to a pivot portion 48 projecting from a crank member 50 that is pivotally connected to an upwardly projecting portion 52 of the base 18 located at the end thereof opposite the pivot portion 30. Means responsive to limited unfolding of the boom members 34 and 44 is shown in FIGURES 2 and 3 for maintaining the horizontal orientation of the platform including a pair of link elements 54 and 56 pivotally connected to thepivot 42 and a pivot 53 longitudinally spaced from the pivot 42. The link elements 54 and 56 are also interconnected with each other by a pin at 60 so as to form a rigid projection point of the positioning boom member 44 to which the leveling link 62 is connected. The leveling link is therefore also pivotally connected at 64 to the platform structure and is therefore operative in response to pivotal displacement of the positioning boom member 44 relative to the column member 34 to vary the pivotal position of the platform structure on the connecting member 38 which is rigid with the supporting column member 34. It will therefore be apparent that the column member 34 will provide the major support for the platform structure 24 while the positioning boom member 44 will be operative to both control the position of the platform structure relative to the supporting column member 34 and also contribute to the raising of the column member to its elevated or unfolded position.

In order to effect unfolding and elevation of the lifting assembly 20, the power operated system 26 includes a pair of cylinder devices 66 pivotally mounted on the pivot portion 30 of the base 18, on opposite sides of the lever member 28. The cylinder devices 66 slidably mount hydraulically operated pistons connected to piston rods 68. The piston rods 68 are interconnected by a suitable pin connection 70 to a pair of foldable links 72 and 74 which are pivotally connected to the lever member 28 and the column member 34 respectively in spaced relation to the pivotal connection on pivot portion 32. Accordingly, extension of the piston rod 68 from the position shown in FIGURE 2 to the position shown in FIGURE 3 will cause the foldable links 72 and 74 to unfold and thereby pivotally displace the column member 34 with respect to the lever member 28. It will, of course, be apparent that since the column member 34 is pivotally connected at its upper end by means of the connecting member 38 to the boom member 44, the limited unfolding of the boom members with respect to each other and the constraint so imposed will cause upward pivoting of the lever member 28. Power cylinder devices 76 are therefore pivotally mounted on the base 18 on opposite sides of the crank member 50 and operatively connected thereto for upwardly displacing the crank member 50 in the same direction as the lever member 28 in order to upwardly elevate the positioning boom member 44 at an unfolding angle to the column member 34. The piston rods 78 extended from the cylinder devices 76 are therefore pivotally connected at 80 to the links 82 and 84 respectively connected to the pivot connection on the pivot portion 52 and to the crank member 50 at 86. The links 82 and 84 therefore format point 80 a rigid projection of the crank 50 to which the piston rod 78 is connected for pivotal displacement of the crank. It will be observed that the pivotal mounting of the crank '50 on the base 18 is spaced both horizontally and vertically from the pivotal mounting of the lever member 28 on the base so that parallel alignment of the crank 50 with the column member 34 may be obtained as illustrated in FIGURE 2 enabling the boom member 44 to be disposed in parallel relation to the column member 34 for a more compact folded arrangement. The power cylinders 66 and 76 may therefore cooperate to effect elevation of the platform 24 from the lower position illustrated in FIGURE 2 at a more rapid rate than the relative unfolding movement between the boom members at the upper ends thereof so as to assume the position illustrated in FIGURE 3.

The power system 26 therefore includes any suitable motive source of power 88 operative to drive a pump unit 90. The pump unit 90 may be connected by a discharge line 92 to a two-way control valve 94 operatively connected to the power cylinder devices 66. Accordingly, a supply line 96 connected to the pivot end of both cylinder devices 66 may supply fluid under pressure to the cylinder devices while line 98 is vented to return line 100 for extension of the piston rod when the valve device 94 is properly positioned. Alternatively, the valve 94 may connect the fluid pressure supply through the line 98 to both of the opposite ends of the cylinder devices 66 While venting line 96 through line to reservoir 101 for retraction of the piston rods. The pump discharge line 92 and return line 100 may also be simultaneously but independently connected by means of the two-way valve 102 to the cylinder devices 76 through opposite ends of the cylinder devices 76 through the lines 104 and 106. Accordingly, the cylinder devices 76 may be controllably utilized to supplement the power supply through the cylinder devices 66 for elevating the platform by means of the lift device.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A workmans aerial lift device comprising, base means, foldable lifting means movably mounted on said base means, power operated means mounted on said base means and operatively connected to said foldable lifting means for unfolding thereof, platform means movably supported at an end of the foldable lifting means remote from the power operated means, positioning means mounted on the base means in spaced relation to the foldable lifting means and operatively connected to the foldable lifting means and platform means at said remote end of the lifting means for constrained positioning of the platform means in all positions of the foldable lifting means, and separate power means mounted on said base means and operatively connected to the positioning means and operative to assist unfolding of the foldable lifting means, said foldable lifting means comprising, lever means pivotally mounted on the base means for movement from a folded position on the base means adjacent to the positioning means to a vertical unfolded position away therefrom, non-extensible, elongated column means pivotally connected to the lever means for movement from said folded position parallel to the lever means to said unfolded position, and connecting means mounted on the column means at said remote end for pivotal connection thereof to the platform means and positioning means, said power operated means comprising cylinder means pivotally mounted on the base means, piston means actuated by the cylinder means and foldable linkage means operative- 1y connecting the piston means to the lever means and the column means for unfolding of the foldable lifting means.

2. A workmans aerial lift device comprising base means, foldable lifting means movably mounted on said base means, power operated means mounted on said base means and operatively connected to said foldable lifting means for unfolding thereof, platform means movably supported at an end of the foldable lifting means remote from the power operated means, positioning means movably mounted in the base means in spaced relation to the foldable lifting means and operatively connected to the foldable lifting means and platform means adjacent said remote end of the lifting means for horizontally positioning the platform means for all positions of the foldable lifting means and separate power means mounted on said base means and operatively connected to the positioning means for upwardly extending the positioning means and thereby supplemeting the unfolding of the foldable lifting means by the power operated means, said foldable lifting means comprising lever means pivotally mounted on the base means for movement from a position on the base means adjacent to the positioning means to a vertical position away therefrom, non-extensible, elongated column means pivotally connected to the lever means for movement from a folded position parallel to the lever means to an extended position and connecting means mounted on the column means at said remote end for pivotal con nection thereof to the platform means and positioning means, said power operated means comprising cylinder means pivotally mounted on the base means, piston means actuated by the cylinder means and foldable linkage means operatively connecting the piston means to the lever means and the column means for unfolding of the foldable lifting means, said positioning means comprising crank means pivotally mounted on the base means for movement in a direction opposite to that of the column means, elongated rigid boom means pivotally connected to the crank means for movement from a position parallel to the foldable lifting means in the folded position to an extended position at an angle thereto, and connecting means mounted at one end of the boom means for piv0tally connecting the boom means to the foldable lifting means and link connecting the boom means to the platform means for positioning thereof relative to the lifting means.

3. The combination of claim 2 wherein said separate power means comprises fluid operated means pivotally mounted on the base means and operatively connected to the crank means for upward extension thereof.

4. A Workmans aerial lift device comprising base means, foldable lifting means movably mounted on said base means, power operated means mounted on said base means and operatively connected to said foldable lifting means for unfolding thereof, platform means movably supported at an end of the foldable lifting means remote from the power operated means, positioning means mount ed on the base means in spaced relation to the foldable lifting means and operatively connected to the foldable lifting means and platform means at said remote end of the lifting means for constrained positioning of the platform means in all positions of the foldable lifting means and separate power means mounted on said base means and operatively connected to the positioning means and operative to assist unfolding of the foldable lifting means, said power operated means comprising cylinder means pivotally mounted on the base means, piston means actuated by the cylinder means and foldable linkage means operatively connecting the piston means to the foldable lifting means for unfolding of the foldable lifting means.

5. A workmans aerial lift device comprising, base means, foldable lifting means movably mounted on said base means, power operated means mounted on said base means and operatively connected to said foldable lifting means for unfolding thereof, platform means movably supported at an end of the foldable lifting means remote from the power operated means, positioning means movably mounted in the base means in spaced relation to the foldable lifting means and operatively connected to the foldable lifting means and platform means adjacent said remote end of the lifting means for horizontally positioning the platform means for all positions of the foldable lifting means and separate power means mounted on said base means and operatively connected to the positioning means for upwardly extending the positioning means and thereby supplementing the unfolding of the foldable lifting means by the power operated means, said positioning means comprising crank means pivotally mounted on the base means, elongated rigid boom means pivotally connected to the crank means for movement from a position parallel to the foldable lifting means in the folded position to an extended position at an angle thereto, and connecting means mounted at one end of the boom means for pivotally connecting the boom means to the platform means for positioning thereof relative to the lifting means.

6. The combination of claim 5 wherein said separate power means comprises fluid operated means pivotally mounted on the base means and operatively connected to the positioning means for upward extension thereof.

7. An aerial lift device comprising, support means, a pair of boom members of different fixed lengths, pivotal connecting means operatively connecting said boom members for constraining relative angular movement therebetween, crank means pivotally connecting said boom members to the support means in spaced relation to each other, a platform operatively mounted on said pivotal connecting means, means responsive to constrained relative angular movement of the boom members for maintaining said platform in a horizontal orientation, and power means for imparting relative movement between one of said boom members and the crank means and between the crank means and the supporting means to produce said constrained relative angular movement causing elevation of both of said boom members from retracted positions on the support means to extended positions spaced there above.

8. The combination of claim 7, wherein said power means comprises, means mounted on the support means and operatively interconnected with said crank means and one of said boom members for displacement of said boom member in one rotational direction from parallel relation to the support means in the retracted position thereof and separate means operatively connecting the support means to the crank means for rotation thereof in the other rotational direction to displace the other of said boom members in said one rotational direction from parallel relation to said one boom member.

References Cited in the file of this patent UNITED STATES PATENTS 2,724,620 Johnson Nov. 22, 1955 2,815,250 Trump Dec. 3, 1957 2,970,667 Bercaw Feb. 7, 1961 2,996,196 Podlesak Aug. 15, 1961 

1. A WORKMAN''S AERIAL LIFT DEVICE COMPRIING, BASE MEANS, FOLDABLE LIFTING MEANS MOVABLY MOUNTED ON SAID BASE MEANS, POWER OPERATED MEANS MOUNTED ON SAID BASE MEANS AND OPERATIVELY CONNECTED TO SAID FOLDABLE LIFTING MEANS FOR UNFOLDING THEREOF, PLATFORM MEANS MOVABLY SUPPORTED AT AN END OF THE FOLDABLE LIFTING MEANS REMOTE FROM THE POWER OPERATED MEANS, POSITIONING MEANS MOUNTED ON THE BASE MEANS IN SPACED RELATION TO THE FOLDABLE LIFTING MEANS AND OPERATIVELY CONNECTED TO THE FOLDABLE LIFTING MEANS AND PLATFORM MEANS AT SAID REMOTE END OF THE LIFTING MEANS FOR CONSTRAINED POSITIONING OF THE PLATFORM MEANS IN ALL POSITIONS OF THE FOLDABLE LIFTING MEANS, AND SEPARATE POWER MEANS MOUNTED ON SAID BASE MEANS AND OPERATIVELY CONNECTED TO THE POSITIONING MEANS AND OPERATIVE TO ASSIST UNFOLDING OF THE FOLDABLE LIFTING MEANS, SAID FOLDABLE LIFTING MEANS COMPRISING, LEVER MEANS PIVOTALLY MOUNTED ON THE BASE MEANS FOR MOVEMENT FROM A FOLDED POSITION ON THE BASE MEANS ADJACENT TO THE POSITIONING MEANS TO A VERTICAL UNFOLDED POSITION AWAY THEREFROM, NON-EXTENSIBLE, ELONGATED COLUMN MEANS PIVOTALLY CONNECTED TO THE LEVER MEANS FOR MOVEMENT FROM SAID FOLDED POSITION PARALLEL TO THE LEVER MEANS TO SAID UNFOLDED POSITION, AND CONNECTING MEANS MOUNTED ON THE COLUMN MEANS AT SAID REMOTE END FOR PIVOTAL CONNECTION THEREOF TO THE PLATFORM MEANS AND POSITIONING MEANS, SAID POWER OPERATED MEANS COMPRISING CYLINDER MEANS PIVOTALLY MOUNTED ON THE BASE MEANS, PISTON MEANS ACTUATED BY THE CYLINDER MEANS AND FOLDABLE LINKAGE MEANS OPERATIVELY CONNECTING THE PISTON MEANS TO THE LEVER MEANS AND THE COLUMN MEANS FOR UNFOLDING OF THE FOLDABLE LIFTING MEANS. 